Pulse generator



Nov. 19, 1946. R, c, LOCKE 2,411,442

PULSE GENERATOR Filed Dec. 1, 1943 Figl. 7

l0 F1) 9 M 7'0 ACZSOUECE PI .2. /2 Z Inventor: Raym 0nd C. Locke,

is Attorney.

Patented Nov. 19, 1946 PULSE GENERATOR Raymond 63. Locke, Schenectady, N. Y., assignor to General Electric Company, a corporation of a New York Application December 1, 1943, Serial No. 512,473

My invention application is a continuation in part of my parent application Serial No. 465,662, filed November 16, 1942, entitled Directive radiant energy apparatus, and which is assigned to the assignee of this present application.

My present invention has for one of itsjobjects to provide a novel pulse generating system having means for producing pulses spaced equally in time and of alternate polarity.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however. both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawing in which Fig. 1 represents an embodiment of my invention, Fig. 2 represents the character of pulse wave produced thereby and Fig. 3 shows a second embodiment of my invention.

Referring to Fig. 1 of the drawing, I. have shown my pulse generator! connected between a suitable source of alternating current of, for example, 400 cycles and which may be connected to the terminals 2 and a load device comprising resistance 3. The generator I comprises a pair of diodes 4 and 5, which may be arranged in a single envelope 6 and the cathodes of which are connected to the opposite terminals of the secondary winding of transformer I through resistance 8. The anodes are likewise connected to the opposite terminals of the secondary winding of the transformer through a second resistance 9, the two resistances 8 and 9 having a terminal in common connected to one terminal of the secondary winding of the transformer. Thus the anode of diode is connected to the cathode of diode 4 through the two resistances 9 and 8. This anode of diode 5 is alsoconnected to the cathode of diode 4 through two capacitances l0 and H. The load device 3 has one terminal connected to the point between cone densers Ill and II and its other terminal connected to the point between resistances 8 and 9.

In the operation of this circuit the two diodes are alternately conducting. When either diode conducts, it produces a potential on its respective resistance 8 or 9, which in turn charges the corresponding condenser H or H). The time constant of each of these condensers and the respective resistance is such that this charge is held over between the conducting periods of the discharge device, leaking oii only gradually through the respective resistance. The result is that the anode of each diode is biased negatively relative to its cathode by an amount dependent upon the magnitude of the impressed voltage and current flows through each diode only during a 4 Claims. (Cl. 250--27) portion of a half cycle when its anode is positive, being zero for an interval at the beginning of the half cycleand for another intervaljust prior to the end of the half cycle. That is, current flows in the respective device only when the, steady bias is overcome by the impressedalternating voltage. The duration of these intervals is substantially constant during variations in intensity of the voltage supplied at terminals 2 since the bias voltage automatically developed on the respective condenser increases in the same ratio as the impressed alternating voltage. Thus current pulses of the form indicated at E2 and I3 in Fig. 2 are produced across the resistance 3., these pulses being of alternate polarity and each pulse being shorter than a half cycle of the 400 cycle wave supplied at terminals 2,. the successive pulses being spaced apart in time by a period of substantially zero current indicated at l4. As the intensity of the alternating voltage supplied at terminals 2 increases the intensity of the pulses l2 and I3 increases, the charge on the condensers l0 and II increases in the same ratio with the impressed voltage, and the duration or the difierent pulses thus remains constant. e 7

My invention has particular utility in radio echo apparatus in which the position of remote objects. is indicated upon the screen of a cathode ray device. I have indicated in Fig. l a cathode ray device l6' having on its right end, as shown in Fig. 1, a viewing screen which I have represented bythe circle. [1. This cathode, ray oscillograph has vertical deflecting plates l8 and horizontal deflecting plates l9 between whichvolt: ages may be applied through terminals 2!! and 2| so related as to produce a spot 22' on the screen of the cathode ray device which moves over the screen in accordance with the position of the remote object to be indicated. In certain appli-- cations, especially where the object tobe indicated is an airplane, it is desirable that the spot have a form suggestive of an airplane. Thisresult is readily effected for the use of myinven:

tion in which the pulses represented in Fig. 2 are produced across the resistance 3 and hence be-' tween the horizontal deflecting plates it where they operate to deflectthemy to the right d'llI'". 7

ing the positive pulses and to the left during the negative pulses while leaving the ray centered form very suggestive of an airplane.

upon the spot22 during theshortintervals It. Thus the spot 22 is more illuminated thanthe projections to the right and tothe left from the spot with the result that the spot takes on .a

If desired, the alternating potential applied to the terminals 2 may be varied in intensity .with the range of-the remote object, in which ca'se the pulses l2 and I3 vary in intensity correspondingly thereby varying the lengths of the wings 3 to agree with the distance to the remote target. Thus the wings may be long when the targetis nearby and short when the target is more distant.

Fig. 3 shows a modification of my invention employing triodes in place of the diodes which are capable of producing a wave between their output terminals 25 of substantially the form of the wave illustrated in Fig. 2. Anode-voltage of the 400 cycle frequency and of constant intensity is supplied between the anode" and cathode of'the two triodes through a three-winding transformer having a primary winding 2'! and secondary" windings 28 and 29 The anode circuit for the triode 30 extends from the anode thereof through the winding 28, resistance 33, conductor 35 and cathode resistance 35 which is shunted by a condenser 36 back to the cathode of the diode. Similarly the anode circuit of triode 3'? extends from the anode thereof through winding 29, resistance -38, conductor 34, cathode resistance 40 shunted by a condenser 43 back to the cathode of the discharge device. Windings 28 and 25 are poled oppositely so that when one of the anodes is positive in potential with respect to its cathode, the anode ofthe opposite device is negative with respect to its cathode whereby these devices are alternately conducting. The terminals 2 of Fig. 3 correspond to the terminals 2 of Fig. l and have impressed therebetween the 406 cycle voltage variable in intensity. This voltage is supplied between the control electrodes of the two discharge devices through a three-winding transformer having a'primary winding M and secondary windings 45 and it, these secondary windings also being poled oppositely and being so poled that the control electrodes of the two devices are positivewhen their anodes are positive and negativewhen their anodes are negative. Thus pulses of current flow alternately in the two devices and through respective resistances 33 and 33, these pulses of current producing a bias voltage, on the cathode resistances 35 and 48 shunted by the respective condensers 36 and it. These condensers are of sufiicient capacitance that this bias voltage is maintained during the intervals when the anodes of the devices are negative and the. current is interrupted. This bias voltage issufficiently great that a delay is produced in each half cycle of thealternating current wave supplied to the windin 27 before thedischarge device becomesvconducting, and similarly the discharge device becomes nonconducting by reason of this bias voltage prior to termination of the positive half cycle. Thus the pulses of current flowing in the'two devices are shorter than a half cycle of the. alternating current wave with the result that the portions M of maintain the ray of the cathode ray tube at its center position 22 thereby producing the bri ht 4 ferent modifications both in the circuit arrangement and in the instrumentalities employed may be' -made, and I contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

"What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, a source of alternating electromotiveforce of varying intensity, a pair of diodes connected across said source in opposite sense the anode of one diode and cathode of the other being connected together through a resistance path and a capacitance path, and a load circuit connected between an intermedaite point on said resistance path and an intermediate point on (said capacitance path, said resistance and capacitance paths being so proportioned that said alternating)electromotive force of varying intensity is reproduced in said load circuit as pulses of alternating polarity and correspondingly varying intensity and spacedapart in-time by substantially constant amounts as the intensity 0 said electromotive force increases. 1 a V, a 2. In combination, a source of alternating voltage, a pair of unilateral conducting devices.

means to supply said voltage to said devicesin opposite sense, means responsive to rectified cure rent flowing in each of said devices to produce a steady unidirectional voltage across the respective device varying in intensity with, but slower than, variations in intensity of said alternating voltage and poled to prevent flow therein during periods when the instantaneous. intensity ofsaid alternating voltage is less than said steady voltage, an output circuit connected to said devices in which current pulses occur only during periods when the instantaneous intensity of said alternating voltage exceeds said unidirectional voltage, and signal indicating means controlled by said pulses. 3. The combination, ina system to generate pulses spaced apart in time and alternating in polarity, of a pair of electron discharge devices, means to supply alternating current to said (16-,

vices to render said devices alternately conducting, means responsive to current in said'devices to produce a bias opposing the flows-f current in said devices until overcome by thealternating supplied by said'first means whereby 1e pulses of current flowing in said two devices arespaced apart by a desired time interval, a load circuit, and means to supply to said load circuit potential of constant magnitude during said desiredtirne intervals and varying in opposite directhe wave occur which in the operation described 3 has the advantage that it may have high im that I do not wish to be limited thereto since diftions from said magnitude in response to said current pulses in the respective devices.

4. The combination, in a system to generate pulses spaced apart in time and alternating in polarity, of a, pair of electron discharge devices each having an anode, and a cathode, a parallel combination of resistance. and capacitance connected between the anode of one of saiddevices and the cathode of the otheiya load circuit'connected between an intermediate point on said capacitance and an. intermediate point on said resistance, and a source of alternating electromotive force connected in aninput distinct from said load circuit and extending from one of said intermediate points through said source to the cathode of said one of said devices and to the anode of said other device; g

RAYMOND. c. LOCKE. l I 

